| Bohai Sea is the only nearly-closed inner sea in our country, which is composed of three important bays. Liaodong Bay is in the north of it, Bohai Bay is in the west, and Laizhou Bay is in the south. These bays are the spawning,feeding and fattening grounds for fishes, shrimps and shellfishes, and they are the important provenance regions of producing marine biological resources, which play an important role in Chinese fishery waters. Recent years, due to the influences of marine pollution, over-fishing and other factors, the species and the quantity of fishery resources have decreased rapidly since 1990s, and the weaken tendency is still going on. Many good spawning,fattening grounds have lost their fishery functions. The capability of recovering to normal level of fishery resources has been weakened. The marine ecological environment has been becoming worse and worse. In order to protect the fishery germplasm resources and their environment, the Ministry of Agriculture declared at the end of 2007 that Liaodong Bay,Bohai Bay and Laizhou Bay have been the National Reserves for fishery germplasm resources.Based on the data of quartic cruise surveys( in May 2007,Aug 2007, May 2008,Aug 2008) in Bohai Sea fishery waters, this paper carries on a systematical analysis and evaluation of marine ecological environment from three aspects: the seawater environment,the surface sediment environment and the biological environment, and places great emphasis on the integrative evaluation of Bohai Bay's environment. This study presents the current environment state of Bohai Sea, according to this, it is possible for the government to make a plan to recover fishery resources. The study also provides references to the treatment of marine pollution and to sustainable exploiture of marine fishery resources.1 The state of seawater environmentThis article has analyzed physical and chemical factors of the seawater in three fishery bays, and showed the variation characteristics of different time and districts. From the aspect of single-factor assessment,Bohai Sea fishery waters are mainly polluted by DIN(Inorganic Nitrogen nutrient), PO4-P ( Phosphorus nutrient), COD (Chemical Oxygen Demand) and petroleum, the average concentrations of DIN and PO4-P in Bohai Bay's seawater both exceeded the first grade criterion of seawater quality during quartic investigations. Taking DIN,PO4-P,COD as the evaluation indices of eutrophic, the result indicates that the eutrophic pollution is serious in Bohai Bay, Liaodong Bay and Laizhou Bay are in a good state on the whole. Taking DIN,PO4-P,COD,DO(Dissolved Oxygen) as the evaluation indices of organic pollution, the result shows that the organic pollution is the worst in Bohai Bay, Liaodong Bay is in a good state and Laizhou Bay is in a state of elementary pollution. The study makes an evaluation of the seawater environment quality with the composite index, the comprehensive assessing result presents that the seawater in Bohai Bay is badly polluted, Laizhou Bay is in a moderate pollution state, while Liaodong Bay is in a light pollution situation.2 The state of sediment environment & The potential ecological risk assessmentWith the single-factor index and the composite index, this article has analyzed and assessed the sediment environment in Bohai Sea fishery waters, and has assessed the potential pollution risk of surface sediment which is caused by heavy metals by making use of the method of potential ecological risk assessment which was proposed by Lars Hankanson from Sweden The result shows that the sediment environment of the three bays is in a situation of light pollution on the whole. The potential ecological risk of sediment environment is at a low level. The potential risk degree among these bays follows the order: Liaodong Bay>Laizhou Bay>Bohai Bay. The pollution problem of Hg & Cd in surface sediments in Liaodong Bay is notable, while the pollution of Cd is notable in Laizhou Bay, and Bohai Bay is notable with the pollution of As,Hg & Cd.3 The state of biological environmentOn the whole, the seawater in investigation areas in Bohai Bay is rich of chlorophyll-a. From the perspective of Chla analysis, the Bohai Bay fishery waters is eutrophic. There were 51 species belonging to 24 genera of phytoplankton in the investigation areas. Among them, 48 species of 21 genera were Bacillariophyta, which accounted for the larger percentage, and 3 species of 3 genera were Pyrophyta, which accounted for the less species. The seasonal distribution of phytoplankton has such characteristic: In summer(in August) the biomass of phytoplankton is much larger than that in spring(in May). This feature reflects the law of phytoplankton biomass'seasonal variation. There were 17 species belonging to 6 genera of zooplankton in investigation areas, which were mainly composed of inshore-caldus category and estuarine low-salt category. The representative species were Sagitta crassa, Calanus sinicus Brodsky, Acartia pacifica ,Acotes chinensis,et al. Assessing from the aspect of entire plankton environment, Bohai Bay has already been in the state of pollution: The investigation areas of Bohai Bay was in a badly polluted state in May 2007 & May 2008, compared to in a light polluted state in August 2007 and in a moderate polluted state in August 2008. At the same terms in 2008 compared with in 2007, the composite evaluation index for plankton environment was becoming higher, the degree of pollution was becoming worse.4 The comprehensive eco-environment assessment of Bohai Bay with principal component analysisBased on the monitoring results of water quality,surface sediment and plankton in fishery waters of Bohai Bay in May and August of 2008, a comprehensive assessment is given on the eco-environment quality applying principal component analysis. The assessing result shows that the comprehensive quality of eco-environment in Bohai Bay was bad, it was at the"bad"level in May of 2008 and at the"worst"level in August of 2008, and it was worse in summer than in spring. Compared the contributing rates of water quality, sediment and plankton indices, the contributing rate of water quality index was the highest in Bohai Bay. DIN and PO4-P were the main pollution indices in Bohai Bay which influence the eco-environment quality.
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